Patent GB-756712-A (GB)
Title: Improvements in method and apparatus for forming tyres
IPC: B29D30/06
Filed: 1954-06-28
Abstract: 756,712. Moulding tyres. UNITED STATES RUBBER CO. June 28, 1954 [Aug. 10, 1953], No. 18867/54. Class 87(2) A band form tyre carcass, with or without a tread, of rubber and fabric is shaped to approximately tyre shape without substantially stretching the fabric, then the beads and a substantial portion of the sidewalls of the carcass are clamped between unyielding surfaces whilst the fabric is in a substantially unstretched condition, then the remainder of the carcass is expanded to final tyre shape and vulcanized by heat whilst the beads and sidewall portions are clamped. As described the unyielding surfaces are constituted by the metal part of a metal-plusinflatable-tube core and the metal of mould halves. A press, Figs. 1, 4 and 12, for shaping and vulcanizing a tyre carcass comprises a stationery lower mould half 11, a movable upper mould half 12 and a special core 18. This core is annular in shape. The inner half of the annulus is formed by four steel arcuate segments 19, 20, 21, 22, and the outer half is formed by an annular rubber tube 23 which surrounds all the segments and is attached to segments 19, 20. The four steel segments are collapsible, segments 21, 22 being movable radially inwardly and axially downwardly and segments 19, 20 being movable radially inwardly only. When the core is collapsed (as shown in Fig. 4, plan view) that portion of the tube 23 that is normally supported by the segments 21, 22 is pulled into the space between 19 and 20 by springs 36...39. Segments 19, 20 are' moved in and out by a fluid pressure cylinder 47 acting though rack 48, pinion 49, shaft 53, gears 50, 51, shaft 54, pinion 46 and racks 44, 45. Segments 21, 22 are similarly moved in and out by fluid pressure cylinder 69 and rack-andpinion means 68, 64, 65, and are also raised and lowered by fluid pressure cylinder 70. The core 18 as a whole is supported on a pillar 43, 71 which may be raised and lowered by means of a fluid pressure cylinder 73. Operation:-(1) The press being open as in Fig. 1, the parts 19, 20 of the core 18 being in the inner (retracted) position and the core parts 21, 22 being retracted and in the lowered position, a tyre carcass C is fitted over the core. (2) Cylinder 47 is operated to expand the core parts 19, 20. (3) Cylinder 70 is operated to raise the core parts 21, 22 into horizontal alignment with core parts 19, 20 (4) Cylinder 69 is operated to expand core parts 21, 22 into engagement with parts 19, 20 to complete the core. (5) Heated fluid under pressure is admitted to tube 23 through pipes 34, 35 to inflate it to approximate tyre shape without stretching the fabric of the carcass. (6) Mould half 10 closes and pressure in cylinder 73 is released to allow the core 18 to descend, the press being thus closed as in Fig. 12 and the beads and half of the carcass sidewalls being clamped between the steel core parts and the mould halves. The mould halves are heated by steam &c. in passages 16, 16a, 17, 17a. Initially steam may be circulated only through passages 16, 16a so that the bead areas are vulcanized before the remainder of the carcass. (7) After a few seconds the pressure in tube 23 is increased to shaping pressure. A control circuit system may energize the various fluid pressure cylinders in time sequence. Modification:-After the carcass has been clamped a tread-T, Fig. 13, may be injected on to the carcass in the mould whilst a slight pressure is present in tube 23, the pressure in this tube being increased after injection. Specification 708,856 is referred to.